1. Field of the Invention
The invention relates to fluid couplings for fluid actuated extensible structure and more specifically to a hydraulic coupling in a hydraulic line of a lift truck upright.
2. Description of the Prior Art
Over the years a persistent problem in fluid actuated extensible structures, such as multi-stage uprights for lift trucks, has been to provide a construction which affords the operator of the apparatus good visibility through the structure. Heretofore, various means have been devised for improving operator visibility through lift truck uprights such as is disclosed in U.S. Pat. Nos. 2,855,071, 3,213,967, 3,394,778, U.S. Pat. No. Re. 27,731, and in copending U.S. Application Ser. No. 017,779, filed Mar. 8, 1979 now abandoned, all of which are assigned to the assignee of the present application.
Generally, in the above-discussed prior art, as shown in FIG. 8 of Application Ser. No. 017,779, supra, fluid communication between a primary cylinder and a secondary cylinder is provided by a hose that is routed from the base of the secondary cylinder to the top of the upright, over a sheave and then back down to the base of the primary cylinder.
Frequently the design of the upright dictates that the hose routed over the sheave at the top of the upright must bend below the minimum recommended bend radius which leads to shortened hose life. To minimize the bend radius the hose diameter can be reduced but this creates increased back pressure and adds inefficiency to the hydraulic system. Additionally, the above-described hose connection reduces visibility through the upright.